Lipogenesis and stearoyl-CoA desaturase gene expression and enzyme activity in adipose tissue of short- and long-fed Angus and Wagyu steers fed corn- or hay-based diets

Abstract

Angus and Wagyu steers consuming high-roughage diets exhibit large differences in adipose tissue fatty acid composition, but there are no differences in terminal measures of stearoyl-CoA desaturase (SCD) activity or gene expression. Also, adipose tissue lipids of cattle fed corn-based diets have greater MUFA:SFA ratios than cattle fed hay-based diets. We hypothesized that any changes in SCD gene expression and activity would precede similar changes in adipose tissue lipogenesis between short- and long-fed endpoints. Furthermore, changes in SCD activity and gene expression between production endpoints would differ between corn- and hay-fed steers and between Wagyu and Angus steers. Angus (n = 8) and Wagyu (n = 8) steers were fed a corn-based diet for 8 mo (short-fed; 16 mo of age) or 16 mo (long-fed; 24 mo of age), whereas another group of Angus (n = 8) and Wagyu (n = 8) steers was fed a hay-based diet for 12 mo (short-fed; 20 mo of age) or 20 mo (long-fed; 28 mo of age) to match the end point BW of the corn-fed steers. Acetate incorporation into lipids in vitro was greater (P < 0.01) in corn-fed steers than in hay-fed steers and tended (P = 0.06) to be greater in Wagyu than in Angus s.c. adipose tissue because the rate in Wagyu was twice that of Angus adipose tissue in the corn-fed, short-fed steers. There were diet x end point interactions for lipogenesis in i.m. and s.c. adipose tissues (both P < 0.01) because lipogenesis was 60 to 90% lower in the long-fed cattle than in short-fed cattle fed the corn-based diet. The greatest SCD enzyme activity in Angus s.c. adipose tissue was observed at 24 mo of age (corn-based diet), but activity in Wagyu adipose tissue was greatest at 28 mo of age (hay-based diet; breed x diet x end point interaction, P = 0.08). For short- vs. long-fed endpoints in Angus, s.c. adipose tissue SCD activity was less (hay diet) or the same (corn diet). Conversely, SCD gene expression was greatest in long-fed Wagyu steers fed the hay- or corn-based diets (breed x end point interaction; P < 0.01). Contrary to our hypotheses, SCD activity increased over time, whereas lipogenesis from acetate decreased. However, the developmental pattern of SCD gene expression and activity differed markedly between hay-fed Angus and Wagyu adipose tissues, which may explain the differences in the MUFA:SFA ratios observed in adipose tissues from these cattle.

Expression of genes involved in adipogenesis and lipid metabolism in subcutaneous adipose tissue and longissimus muscle in low-marbled Pirenaica beef cattle

“…Chung et al (2007) also observed greater adipocyte density (more adipocytes/100 g tissue) in SC and IM AT in corn-fed long-fed (from 8 to 24 months of age) Angus steers as compared with corn-fed short-fed (from 8 to 16 months of age) steers, suggesting the emergence of newly formed adipocytes or a population of small cells in the AT of steers fed non-structural carbohydrate for a longer period. Adipocyte proliferation could, as well, be related to mature adipocyte size, as suggested by studies showing that on reaching a critical volume rat adipocytes secrete factors that recruit new adipocytes (Marques et al, 1998), increasing tissue storage capacity.…”

“…For instance, Chung et al (2007) observed that SC fat thickness and marbling scores increased over time in corn and hay-fed steers and showed that long-fed (16M), grain-fed cattle produced higher quality carcasses with softer fat than short-fed (8M), grain-fed cattle, while Moura et al (2013) reported that steers fed a high-fat diet (2.7% v. 7.1%) resulted in downregulation of proteins involved in preadipocyte growth arrest and concluded that preadipocyte proliferation was favoured over differentiation and may have been more intense in both the visceral and SC ATs in steers fed with high-fat diet.…”

Feeding wet distillers grains plus solubles contributes to sarcoplasmic reticulum membrane instability

“…Perhaps, the 0% WDGS steers needed to generate more MUFA from SFA because less PUFA was available in the plasma to incorporate in the organelle membrane. The other possibility is that the 50% WDGS diet (high in PUFA) may have suppressed the stearoylCoA desaturase gene, which is the gene that encodes for delta-9-desaturase (Chung et al 2007).…”

Evaluación de panel SNP en genes candidatos de vías metabólicas para carne en Hereford

“…El grupo PB fue el que presentó los menores pesos de canal caliente en relación al grupo CA. Al tener menor contenido de ácidos grasos mono-insaturados (principal- mente ácido oleico, C18:1, cis-9) sugiere que podría haber una depresión de la actividad de las desaturasas (Chung et al, 2007). Baeza et al (2012) encontraron efectos significativos de los polimorfismos SRPR sobre la actividad de las desaturasas en novillos Brangus alimentados a pasto, destacando la importancia de los procesos de señalización celular para el transporte y la activación temprana de la proteína, y un papel de apoyo para estos mecanismos en la variabilidad de la composición y perfil de ácidos grasos en la carne bovina.…”